Bug 1793749 - Build ICU with the implicithan collation root. r=anba

Makes ICU data 353 KB smaller.

Differential Revision: https://phabricator.services.mozilla.com/D160345

intl/icu/data_filter.json

@@ -1,4 +1,5 @@
 {
+    "collationUCAData": "implicithan",
     "featureFilters": {
         "brkitr_dictionaries": {
             "filterType": "exclude"

js/src/tests/non262/Intl/Collator/implicithan.js

@@ -0,0 +1,17 @@
+// |reftest| skip-if(!this.hasOwnProperty("Intl"))
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+let scrambled = ['𠙶', '𠇲', '㓙', '㑧', '假', '凷'];
+
+// Sort first by block and then by radical-stroke inside each block.
+// This matches the ICU/ICU4X implicithan root order, which is used
+// by Chrome as of October 2022. (As of October 2022, Safari uses
+// the unihan root order, which uses more data but uses radical-stroke
+// across blocks.)
+const byBlock = ['假', '凷', '㑧', '㓙', '𠇲', '𠙶'];
+
+scrambled.sort(new Intl.Collator().compare);
+assertEqArray(scrambled, byBlock);
+
+reportCompare(0, 0, 'ok');